If you exceed the $75 exemption for less than US$3,000, you must pay duties and taxes. There is a flat 16% rate of duties and taxes and you must fill out the payment form intended for it, which is available at the Customs counter.

If the amount of the goods is over the US$3,000, then you must hire the services of a customs broker, who will present the legal forms to pay the duties and taxes (you can ask where to reach one at the Customs Office).